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The Science of Addictive Junk Food

Michael Moss, a Pulitzer Prize–winning investigative reporter at The New York Times, just wrote a book called Salt Sugar Fat.

Every year, the average American eats thirty-three pounds of cheese (triple what we ate in 1970) and seventy pounds of sugar (about twenty-two teaspoons a day). We ingest 8,500 milligrams of salt a day, double the recommended amount, and almost none of that comes from the shakers on our table. It comes from processed food. It’s no wonder, then, that one in three adults, and one in five kids, is clinically obese. It’s no wonder that twenty-six million Americans have diabetes, the processed food industry in the U.S. accounts for $1 trillion a year in sales, and the total economic cost of this health crisis is approaching $300 billion a year.

In 2011, The New England Journal of Medicine published a study that shed new light on America’s weight gain. The subjects — 120,877 women and men — were all professionals in the health field, and were likely to be more conscious about nutrition, so the findings might well understate the overall trend. Using data back to 1986, the researchers monitored everything the participants ate, as well as their physical activity and smoking. They found that every four years, the participants exercised less, watched TV more and gained an average of 3.35 pounds. The researchers parsed the data by the caloric content of the foods being eaten, and found the top contributors to weight gain included red meat and processed meats, sugar-sweetened beverages and potatoes, including mashed and French fries. But the largest weight-inducing food was the potato chip. The coating of salt, the fat content that rewards the brain with instant feelings of pleasure, the sugar that exists not as an additive but in the starch of the potato itself — all of this combines to make it the perfect addictive food. “The starch is readily absorbed,” Eric Rimm, an associate professor of epidemiology and nutrition at the Harvard School of Public Health and one of the study’s authors, told me. “More quickly even than a similar amount of sugar. The starch, in turn, causes the glucose levels in the blood to spike” — which can result in a craving for more.

If Americans snacked only occasionally, and in small amounts, this would not present the enormous problem that it does. But because so much money and effort has been invested over decades in engineering and then relentlessly selling these products, the effects are seemingly impossible to unwind. More than 30 years have passed since Robert Lin first tangled with Frito-Lay on the imperative of the company to deal with the formulation of its snacks, but as we sat at his dining-room table, sifting through his records, the feelings of regret still played on his face. In his view, three decades had been lost, time that he and a lot of other smart scientists could have spent searching for ways to ease the addiction to salt, sugar and fat. “I couldn’t do much about it,” he told me. “I feel so sorry for the public.”

Still curious? Learn about why we get fat and what you can do about it.